Such a grouping device below a conveying section is shown, for example, in DE 40 36 341 A1, which provides contact elements that engage in the product stream from below, said contact elements being provided on endlessly circulating belt-like or chain-like drive elements. In this case, the distance between a pair of grouping elements corresponds to the size of the subsequent product group, as it is to be supplied to the packaging machines, i.e. one of the elements establishes the front region of the product group in the conveying direction, whilst the rear element engages in the subsequent bottles in order to prevent them from attempting to join in the further conveying of the first group. When the pulse for the further conveying is then activated once again, the group can be conveyed further correspondingly in a separated manner.
A similar development of grouping devices of this type is shown in DE 10 2004 042 474 A1, in this case a bar with dividing fingers being located on the one side of the conveyor belt below the conveying plane and a second bar with a second group of dividing fingers being located on the oppositely situated side, with a method of operation that corresponds, for instance, to the above-described method.
Another development of such a device, in particular concerning the detecting of the respective positioning, is provided by DE 10 2005 063 193 A1.
It has also been shown that the known solutions also have a certain limitation as concerns the variation in different sizes of product groups, for instance when the corresponding installations are converted to other product sizes. Currently, attempts are being made to make it possible to process a large number of different products on such installations. Thus, for example, it is desirable to be able to convert the processing of large-volume 2 liter plastic bottles to the processing of bottles with a volume of only 0.33 liters, such as, for example, is necessary when converting from soft drinks to mineral water.
In this connection, the distances between the dividing elements and their position has to be modifiable as quickly and problem-free as possible, effectively without disturbing the operation of such an installation through long shutdown times.
In addition, it is of considerable importance to be able to control the output of such a device, that is the number of separated product groups per unit time, in as flexible a manner as possible. There is currently no solution known in this connection.
The output of known devices for forming product groups, so-called separating devices, is currently dependent in a substantial manner on the conveyor belt speed and on the diameter of the containers to be processed.
On the one hand this is because the (maximum) speed of the conveyor belt is limited substantially through the characteristics of the containers, for example through their tendency to fall over, which means that the conveyor belt speed is a constant. If, for example, containers with large outer diameters are processed, a certain number of product groups has to be separated off when forming a certain product formation per unit time. If containers with a smaller diameter are then processed, a considerably larger number of product groups has to be separated off to form an identical product formation, as a considerably larger amount of containers per unit time is conveyed through the separating device.
However, as the separating elements necessary for separating the product groups have to move at the conveyor belt speed in a forcible manner at least over part of their path, the speed of the cross-struts in the case of devices from the prior art cannot be increased, which results in the output of such a device being substantially unmodifiable.
The prior art does not contain a proposal to solve this problem.